Topic: 67mm 890cc Piston and ring help!

[Dresda500]

So I’m digging more into this Rickman and wondering if anyone recognizes these pistons. They are 67mm and used with aftermarket sleeves of course. I’d like to re-use them if I can find rings reasonably. They have 1.5/1.5/2.8 ring pack. Has an old school one piece oil ring I’d like to replace with a 3-piece. The previous owner didn’t have deep enough pockets, and not offset so the exh valves have been hitting. Plenty of room to flycut a bit deeper and to the side. The cam has 9.3mm lift and 260 @ 050, 310 adv. . I don’t have the open/close specs but both valves are open 3.5mm at TDC.

[turboguzzi]

kz750 are 66mm, 15mm pin, look similar, so maybe +1 OS pistons?

but they surely never had 1 piece oil rings..... 

[Dresda500]

kz750 are 66mm, 15mm pin, look similar, so maybe +1 OS pistons?

but they surely never had 1 piece oil rings.....

Yes, could very well be an aftermarket KZ750. It has centered valve reliefs, so likely not meant for a CB750 originally. Compression height is very close, just slightly shorter than a factory piston, but it was being run with copper head gasket so how knows if it has been machined. The dome looks too nice for an untouched cast piston. And thicker top rings than factory piston, so for sure an older design, even if a slipper style skirt. It has a thick dome. Piston and pin is 225g.
61mm piston/pin is 207g
61.50mm F2 piston at 199g.

[Dresda500]

And all it took was to put on my glasses and remove the piston pin…😂 They are Henry Abe 900 kit pistons…or that’s what they were called even if only 890cc. There is HAIND and TOHO cast in the inside skirt that I didn’t see at first glance. HAIND stands for Henry Abe Industries. As mentioned in the below thread, rings were whatever….they have Honda 2.8mm oil rings but larger 1.5 mm top rings. Both are available but not sure if I can find in one set. Don’t really want to buy 8 sets of rings to make 4. I’ll send some mails and see if anyone can make a proper set that is cost efficient for an older heavy piston. This will just be a street bike motor so don’t need full race spec rings

http://forums.sohc4.net/index.php?topic=15624.0

[Jerry Rxman Griffin aka MuthaF'er]

I second on the Abe kit. I sent one of mine off to Total Seal for fitment some years back. Reach out to me after October 1 and I will get you the part numbers. I am out of the country currently and have no access to the info. I still have the oil rings after switching to the 3 piece as you want to do. Extra pistons plus maybe the NOS head gasket too.

[RAFster122s]

The rings were a weak spot on the Henry Abe design from what I have read. Might be cheaper to just pick up a set of pistons and rings and gasket from Cruisin’ Image

[MRieck]

I second on the Abe kit. I sent one of mine off to Total Seal for fitment some years back. Reach out to me after October 1 and I will get you the part numbers. I am out of the country currently and have no access to the info. I still have the oil rings after switching to the 3 piece as you want to do. Extra pistons plus maybe the NOS head gasket too.

Just as an FYI....Total Seal no longer cut ring grooves.

[Don R]

 I was looking at an old set of HA 900's tonight, I wonder if those had been installed in the wrong holes or upside down. I have an 811 kit that was upside down. The rub marks looked similar.
  I'm wondering if there's enough sleeve left to go to 906cc with a 67.5 Dynoman set.

[Jerry Rxman Griffin aka MuthaF'er]

I second on the Abe kit. I sent one of mine off to Total Seal for fitment some years back. Reach out to me after October 1 and I will get you the part numbers. I am out of the country currently and have no access to the info. I still have the oil rings after switching to the 3 piece as you want to do. Extra pistons plus maybe the NOS head gasket too.

Just as an FYI....Total Seal no longer cut ring grooves.

I didn't have to have the grooves cut. They were able to size rings from their inventories based on having my actual piston in hand.

[MRieck]

I second on the Abe kit. I sent one of mine off to Total Seal for fitment some years back. Reach out to me after October 1 and I will get you the part numbers. I am out of the country currently and have no access to the info. I still have the oil rings after switching to the 3 piece as you want to do. Extra pistons plus maybe the NOS head gasket too.

Just as an FYI....Total Seal no longer cut ring grooves.

I didn't have to have the grooves cut. They were able to size rings from their inventories based on having my actual piston in hand.

I figured that Jerry....just wanted to put that info out there. I found out when I was looking for 71.15mm XA ring sets. What are you doing posting stuff......I figured you'd be sitting there watching the clock waiting for the C8.

[Dresda500]

Yes, my first thought was the pistons might have been installed incorrectly, but these have the valve cutouts in the center, which makes me believe maybe they were for another application. These have an F cast into the side on the front and coincides with the correct pin offset, so they were installed correctly. I don’t think I’ll mess with them since they have thick rings and are quite heavy. My aftermarket liners are 70mm OD at the bottom taper, but might try a set of Honda 230CRF 67mm piston as they have the correct 15mm pin and nice thin 1.0/1.2/2.0 rings and compression height is a bit shorter, but can fix that with some cylinder milling.

On another topic, maybe should have its own thread, but…has anyone used a more modern rod and turned down the rod mains from the gigantic 36mm to something more modern? You could offset ground to gain some stroke if wanted as well.

Here’s a #$%*ty pic of the Rickman that this engine is belonging to. This has been running in the Forgotten Era class, ‘73-81…due to its mag wheels and 39mm fork…but isn’t competitive against 1270cc KZ and the big GS bikes. I have plates for it so it will likely due street duty as well . I have a Martin KZ that is competitive in that class so don’t really need this as a pure race bike

[Jerry Rxman Griffin aka MuthaF'er]

I second on the Abe kit. I sent one of mine off to Total Seal for fitment some years back. Reach out to me after October 1 and I will get you the part numbers. I am out of the country currently and have no access to the info. I still have the oil rings after switching to the 3 piece as you want to do. Extra pistons plus maybe the NOS head gasket too.

Just as an FYI....Total Seal no longer cut ring grooves.

I didn't have to have the grooves cut. They were able to size rings from their inventories based on having my actual piston in hand.

I figured that Jerry....just wanted to put that info out there. I found out when I was looking for 71.15mm XA ring sets. What are you doing posting stuff......I figured you'd be sitting there watching the clock waiting for the C8.

Haha Mike. Left Manila and the Thailand elephant ride. I am in Dubai now watching the clock for the Z06 build scheduled for next week. Hot afternoons. 100+ so we return and I am having an 8% Red Horse Filipino tall boy beer. Timing should be good. The 2012 Grand Sport goes on BAT first week of October when I return home. Burg Kalifa tomorrow, Desert safari in 2 more days with Belly Dancer, Bar BQ, and dune buggy and camel ride, etc. Do does this tell you the SOHC4 has some precedence haha

[RAFster122s]

Careful where you put your hands around those belly dancers Jerry, wouldn't want you to lose a hand or something else...

[willbird]

On another topic, maybe should have its own thread, but…has anyone used a more modern rod and turned down the rod mains from the gigantic 36mm to something more modern? You could offset ground to gain some stroke if wanted as well.

There is a youtube channel called "Jims Automotive", the guy has a crank grinder, what you are talking about is right up his alley maybe :-).
Long video here but he has lots of info on his channel, he is the only one I have seen going into detail about grinding crankshafts.

Bill